Probability Fundamentals: From Theory to Practice
Learn how to calculate probabilities, differentiate between outcomes, and grasp the concept of mutually exclusive events. Enhance your knowledge of probability calculations through engaging examples and exercises.
Probability Fundamentals: From Theory to Practice
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Presentation Transcript
Probability OCR Stage 6
Probability • In an experiment, things that can happen are called possible outcomes • Each of these has a possibility
Probability of an event happening • Probability = Required OutcomeTotal Possible Outcomes • i.e. The number of required outcomes divided by the total number of possible outcomes
Getting a 4 on a single dice • There is 1 required outcome – a four • There are 6 possible outcomes • P(4) = 1 The answer may be written as a fraction, decimal or percentage 6 NEVER as “one out of six” The P says, “The probability of”
The probability of not getting a 4? • There are five numbers on the single dice that are not a 4 • There are six possible outcomes • So, P(Not getting a 4) = 5 6
The total probabilities of any event have a total of 1 1/6 + 5/6 = 1 It is important that you notice that the two probabilities add together to give 1 Probability of not getting a 4 on a single dice Probability of getting a 4 on a single dice
Sum of all probabilities equal 1. Example The probability of a football team’s results in the next match are: • P(Win) = 0.3 • P(Lose) = 0.5 • What is the probability of a draw?
Remember the total of all the probabilities is 1 The team must win, lose or draw. • P(Win) + P(Lose) + P(Draw) = 1 • 0.3 + 0.5 + P(Draw) = 1 • 0.8 + P(Draw) = 1 • P(Draw) = 0.2 This is 0.5 This is 0.3
Mutually Exclusive events • Can NOT happen at the same time • Examples • A HEAD and a TAIL when coin is spun • A 6 and an odd number when die rolled • A level 5 and a level 6 on a SAT paper
Example • Sam and Pete play chess • P(Sam wins) = 0.4 • P(Pete wins) = 0.3 • What is P(Draw) ? • 0.4 + 0.3 + P(Draw) = 1 • 0.7 + P(Draw) = 1 • P(Draw) = 0.3
Exercises – to be completed next lesson • OCR Stage 5/6 Text, • Stage 6, Chapter 4, Page 182 • Ex 4.1A • Ex 4.1B • Ex 4.2A • Ex 4.2B